/* Turbo code Test Driver: log_map, random interleaver *//* Creation date : Jan.3 2001    *//* Program written by: Gao yingzi        *//* This program simulates the classical turbo encoding-decoding system on PC. *//* It uses parallel concatenated convolutional codes described in Figure 2.9 in Chapter 2. *//* Two component RSC (Recursive Systematic Convolutional) encoders are used.               *//* First encoder is terminated with tails bits. (Info + tail) bits are scrambled and       *//* passed to the second encoder, while second encoder is left open without tail bits.      *//* Random information bits are modulated into +1/-1, and transmitted through an AWGN channel. *//* Interleavers are randomly generated for each frame. *//* Log-MAP algorithm without quantization or approximation is used. *//* By making use of ln(e^x+e^y) = max (x,y) + ln(1+e^(-abs(x-y))),  *//* the Log-MAP is simplified with a look-up table for the correction term. *//* When the approximation ln(e^x+e^y) = max (x,y) is, we have MAX-Log-MAP. *//* To set the number of iterations, change the globle variable "DECITER". To set the frame length,   *//* the globle variable "FRAMESIZE" should be changed. To simulate a different range of Eb/N0, change *//* the globle variable LOEBNO and HIEBNO, as well as the step size of Eb/No increment. */#include <malloc.h>#include <math.h>#include <stdio.h>#include <stdlib.h>#include <time.h>#define K 3              /* constraint length */#define NUMSTATES 4      /* 2^(K - 1) -- change as required */#define PUNCTURE 1       /* rate increase from 1/3 to 1/2 if puncture=0 */#define INF 1000000      /* set infinity to an arbitrarily large value */ #define PI 3.141592654   /* circumference of circle divided by diameter */#define FRAMESIZE 900    /* how many bits in each test message */#define DECITER 6        /* decoding iteration numbers */ #define LOEBN0 0.0       /* minimum Eb/No at which to test */#define HIEBN0 3.0       /* maximum Eb/No at which to test */#define EBN0STEP 0.5     /* Eb/No increment for test driver *///#define DEBUG            /* test the outputs of the trellis function */void gen01dat(int data_len, int *out_array);void turbo_encd(int g[2][K], int alpha[FRAMESIZE], int *in_array, int puncture, int *turbo_en_out);void addnoise(float eb_ovr_n0, int data_len, int *in_array, float *out_array);void de_multiplex(int alpha[FRAMESIZE], int puncture, float *in_array,			 float *decd1_in_array, float *decd2_in_array);void logmap(int g[2][K], int len_total, int num_decd, float *rec_s, float *L_a, float *L_u);main() {  int i, j, a, iter, t, start;                /* loop variables */  int len_total, msg_length, channel_length;  /* length of I/O files */  int puncture, num_decd;  int alpha[FRAMESIZE] = {0};      /* random interleaver matric */  int *onezer;  int *encoded;                    /* original, encoded array */  float *splusn;                   /* noisy data array */  float *rec_s1;  float *rec_s2;  float *L_a;  float *L_e_1;  float *L_e_2;  float *L_u;  float *L_all;  int *turbout;  FILE *fp;  int m, dec_iter;                 /* m = K - 1,turbo decoding iteration */  float eb_ovr_n0,rate,L_c,bit_errors,temp_bit_errors,frame_errors,e_threshold,e_ber,f_ber; /* various statistics */  int g[2][K] = {{1, 1, 1},     /* 7 */                   {1, 0, 1}};    /* 5 */  fp = fopen("TCC_Binary_PC_data","wa+");  if ((fp = fopen("TCC_Binary_PC_data","wa+"))==NULL){    printf("cannot open file\n");    exit (0);  }  printf("\ng1 = %d%d%d", g[0][0], g[0][1], g[0][2] );  printf("\ng2 = %d%d%d\n", g[1][0], g[1][1], g[1][2] );  fprintf(fp,"\ng1 = %d%d%d", g[0][0], g[0][1], g[0][2] );  fprintf(fp,"\ng2 = %d%d%d\n", g[1][0], g[1][1], g[1][2] );  puncture = PUNCTURE;  rate = (float) 1.0/(2.0 + PUNCTURE);  a = 1;  m = K - 1;  msg_length = FRAMESIZE - m;  len_total = FRAMESIZE;  for (i=0; i<len_total; i++){    alpha[i] = rand() % len_total;    if (i>0) {      for (j=0; j<i; j++)	if(alpha[i] == alpha[j]) i = i-1;    }  }  printf("\nK = %d  puncture = %d  message length = %d\n", K, puncture, msg_length);  fprintf(fp,"\nK = %d  puncture = %d  message length = %d\n", K, puncture, msg_length);  if (puncture > 0) channel_length = ( msg_length + m ) * 3;  else channel_length = ( msg_length + m ) * 2;  onezer = malloc( msg_length * sizeof( int ) );  if (onezer == NULL) {     printf("\n TCC_Binary_PC.c:  error allocating onezer array, aborting!");        exit(1);  }  encoded = malloc( channel_length * sizeof(int) );  if (encoded == NULL) {     printf("\n TCC_Binary_PC.c:  error allocating encoded array, aborting!");     exit(1);  }  splusn = malloc( channel_length * sizeof(float) );  if (splusn == NULL) {      printf("\n TCC_Binary_PC.c:  error allocating splusn array, aborting!");      exit(1);  }  rec_s1 = malloc( channel_length * sizeof( float ) );  if (rec_s1 == NULL) {      printf("\n TCC_Binary_PC.c:  error allocating received symbol 1 array, aborting!");      exit(1);  }  rec_s2 = malloc( channel_length * sizeof( float ) );  if (rec_s2 == NULL) {      printf("\n TCC_Binary_PC.c:  error allocating received symbol 2 array, aborting!");      exit(1);  }  L_a = malloc( len_total * sizeof( float ) );  if (L_a == NULL) {      printf("\n TCC_Binary_PC.c:  error allocating L_a array, aborting!");      exit(1);  }  L_e_1 = malloc( len_total * sizeof( float ) );  if (L_e_1 == NULL) {      printf("\n TCC_Binary_PC.c:  error allocating L_e_1 array, aborting!");      exit(1);  }  L_e_2 = malloc( len_total * sizeof( float ) );  if (L_e_2 == NULL) {      printf("\n TCC_Binary_PC.c:  error allocating L_e_2 array, aborting!");      exit(1);  }  L_u = malloc( len_total * sizeof( float ) );  if (L_u == NULL) {      printf("\n TCC_Binary_PC.c:  error allocating L_u array, aborting!");      exit(1);  }  L_all = malloc( len_total * sizeof( float ) );  if (L_all == NULL) {      printf("\n TCC_Binary_PC.c:  error allocating L_all array, aborting!");      exit(1);  }  turbout = malloc( msg_length * sizeof( int ) );  if (turbout == NULL) {      printf("\n TCC_Binary_PC.c:  error allocating turbo decoding out array, aborting!");      exit(1);  }  for (eb_ovr_n0 = LOEBN0; eb_ovr_n0 <= HIEBN0; eb_ovr_n0 += EBN0STEP) {    start = time(NULL);    L_c = 4 * a * rate * pow(10,eb_ovr_n0/10);      printf("\nreliability = %f",L_c);    fprintf(fp,"\nStart:Reliability = %f",L_c);    printf("   channel length = %d", channel_length);    fprintf(fp,"   channel length = %d", channel_length);    bit_errors = 0.0;    frame_errors = 0.0;    e_ber = 0.0;    f_ber = 0.0;    iter = 0;    if (eb_ovr_n0 <= 3.5) e_threshold = 100; /* +/- 20% */    else e_threshold = 20;                   /* +/- 100 % */    while (bit_errors < e_threshold) {       iter += 1;       gen01dat(msg_length, onezer);       turbo_encd(g, alpha, onezer, puncture, encoded);       addnoise(eb_ovr_n0, channel_length, encoded, splusn);       de_multiplex(alpha, puncture, splusn, rec_s1, rec_s2);       for (i=0; i<2*len_total; i++){ 	 *(rec_s1+i) = 0.5*L_c**(rec_s1+i);	 *(rec_s2+i) = 0.5*L_c**(rec_s2+i);       }          for (i=0; i<len_total; i++){         *(L_a+i) = 0;         *(L_e_1+i) = 0;         *(L_e_2+i) = 0;         *(L_u+i) = 0;       }       for (dec_iter = 0; dec_iter < DECITER; dec_iter++){	 for (i=0; i<len_total; i++)	   *(L_a + alpha[i]) = *(L_e_1 + i);		 num_decd = 1;              /* Decoder one */ 	 logmap(g, len_total, num_decd, rec_s1, L_a, L_u); 	 num_decd = 2;              /* Decoder two */          for (i=0; i<len_total; i++)            *(L_e_2+i) = *(L_u+i) - 2**(rec_s1+2*i) - *(L_a+i);	 for (i=0; i<len_total; i++)	   *(L_a + i) = *(L_e_2 + alpha[i]);	 logmap(g, len_total, num_decd, rec_s2, L_a, L_u);                   for (i=0; i<len_total; i++){            *(L_e_1+i) = *(L_u+i) - 2**(rec_s2+2*i) - *(L_a+i);	 }       }       for (i=0; i<len_total; i++)	 *(L_all + alpha[i]) = *(L_u + i);       for (j=0; j<msg_length; j++){	 if (*(L_all+j)>0.0) *(turbout+j) = 1;	 else *(turbout+j) = 0;       }       temp_bit_errors = bit_errors;          for (t = 0; t < msg_length; t++) {          if ( *(onezer + t) != *(turbout + t) ) {             bit_errors = bit_errors + 1;          } /* end if */       } /* end t for-loop */       if ((bit_errors - temp_bit_errors) > 0) frame_errors = frame_errors + 1;    }    e_ber = bit_errors / (msg_length * iter);    f_ber = frame_errors / iter;    printf("\nframe errors=%f",frame_errors);    printf("\nThe elapsed time was %d seconds for %d frames:  dec_iter=%d",                   time(NULL) - start, iter, dec_iter);    fprintf(fp,"\nThe elapsed time was %d seconds for %d frames:  dec_iter%d",                   time(NULL) - start, iter, dec_iter);    printf("\nAt %1.1fdB Eb/No, ", eb_ovr_n0);    fprintf(fp,"\nAt %1.1fdB Eb/No, ", eb_ovr_n0);    printf("the e_ber was %1.1e the f_ber was %1.1e \n ", e_ber, f_ber);    fprintf(fp,"the e_ber was %1.1e the f_ber was %1.1e\n ", e_ber, f_ber);  } /* end of eb_ovr_n0 loop */  fclose (fp);  free(onezer);  free(encoded);  free(splusn);  free(rec_s1);  free(rec_s2);  free(L_a);  free(L_e_1);  free(L_e_2);  free(L_u);  free(L_all);  free(turbout);  exit(0);}/*******************//* 0/1 Generation  *//*******************/void gen01dat( int data_len, int *out_array ) {  int t;                          /* time */  rand();                         /* re-seed the random number generator */  for (t = 0; t < data_len; t++)  /* generate random data, write to output array */    *( out_array + t ) = (int)( rand() / (RAND_MAX / 2) > 0.5 );}/***************************//* PCCC Turbo code encoder *//***************************/void rsc_encd(int g[2][K], int input_len, int R, int *in_array, int *out_array_0, int *out_array);void turbo_encd( int g[2][K], int alpha[FRAMESIZE], int *in_array, int puncture, int *turbo_en_out){  int i,j,t,tt;                         /* loop variables */  int R;                                /* RSC encoder number */  int yy[3][FRAMESIZE],y[3*FRAMESIZE];  /* make a matrix to store the output */  int *output0,*output1,*output2;  int *rsc2_in_array,*info_array,*unuse;  int m,input_len,len_total;  m = K-1;  len_total = FRAMESIZE;  input_len = len_total-m;  info_array = malloc((input_len)*sizeof(int));  if (info_array == NULL) {     printf("\n turbo_encd:  error allocating info array, aborting!");     exit(1);    }  output0 = malloc((len_total)*sizeof(int));  if (output0 == NULL) {     printf("\n turbo_encd:  error allocating tail_RSC1 output array, aborting!");     exit(1);  }  output1 = malloc((len_total)*sizeof(int));  if (output1 == NULL) {     printf("\n turbo_encd:  error allocating RSC1 output array, aborting!");     exit(1);  }  rsc2_in_array = malloc((len_total)*sizeof(int));  if (rsc2_in_array == NULL) {     printf("\n turbo_encd:  error allocating RSC2 input array, aborting!");     exit(1);  }  unuse = malloc((len_total+m)*sizeof(int));  if (unuse == NULL) {     printf("\n turbo_encd:  error allocating RSC2 useless output array, aborting!");     exit(1);  }  output2 = malloc((len_total+m)*sizeof(int));  if (output2 == NULL) {     printf("\n turbo_encd:  error allocating RSC2 output array, aborting!");     exit(1);  }  for (i=0; i<input_len; i++)    *(info_array + i) = *(in_array + i);  R = 1;  rsc_encd(g, input_len, R, info_array, output0, output1);  /* make a matrix with first row corresponding to info sequence */  /* second row corresponding to RSC #1 s check/parity bits */  /* third row corresponding to RSC #2 s check/parity bits */  for (i=0; i<len_total; i++){    yy[0][i] = *(output0 + i);    yy[1][i] = *(output1 + i);  }  for (i=0; i<len_total; i++)    *(rsc2_in_array + i) = *(output0 + alpha[i]);  R != 1;  rsc_encd(g, len_total, R, rsc2_in_array, unuse, output2);   for (i=0; i<len_total; i++){    yy[2][i] = *(output2 + i);  }	 /* Paralell to serial multiplex to get output vector */  if (puncture > 0){                   /* puncture = 1: unpunctured, rate = 1/3 */    for (i=0; i<len_total; i++){      for (j=0; j<3; j++)	y[3*i+j] = yy[j][i];    }    for (t=0; t<3*len_total; t++)      *(turbo_en_out + t) = y[t];  }  else {                               /* puncture = 0: rate increase from 1/3 to 1/2 */    for (i=0; i<len_total; i++){      y[2*i] = yy[0][i];      if (i%2==0) y[2*i+1] = yy[1][i]; /* even check bits from rsc1 */      else y[2*i+1] = yy[2][i];        /* odd check bits from rsc2 */    }    for (tt=0; tt<2*len_total; tt++)      *(turbo_en_out + tt) = y[tt];  }  free(info_array);  free(output0);